Lifting jack



pt. 23, f947. P. PLUTA ETAL 427,808

y LIF'TING JACK Filed Nov. 2;, 1945 2 sheets-sheet 1 MMM ,M

Patentecl Sept. 23, 1947 LIFTING JACK Peter Pluta and Lester Felders'tein, Rochester, N. Y.

Application November 21, 1945, Serial No. 629,980

8 Claims.

This invention relates to a lifting device or jack, and more particularly to the type of jack operated by a horizontally disposed screw spindle.

It is the object of the present invention to provide a jack of rugged construction which is capable of assuming a wide range of positions between a fully expanded and a compact fully collapsed condition while exhibiting a uniform degree of stability at all of these positions, in order to effectively lift axles of automobiles or other parts thereof, as well as miscellaneous heavy loads.

It is a further object of the invention to provide a jack embodying a novel system of levers between a base and supporting member through which the loadings are transmitted from the latter to the former without straining the actuating mechanism of the jack.

It is a further object of the invention to provide a jack of improved design over the lazy tongs r toggle lever types of jacks known in the prior art and exemplied by such patents as that to Conrad, No. 1,576,721, March 16, 1926, and Marlowe, No. 2,071,470, February 23, 1937.

The invention proceeds upon the principle of providing additional load transmitting levers between the base and the supporting members of the jack in order to relieve the actuating mechanism of the jack from such loads. Furthermore, a stabilizing system of levers may be provided to equalize the loadings between the separate groups of levers at each side and/or end of the jack, which stabilizing system may be correlated between the ends of the jack so that the loads are equalized therebetween, thereby to eliminate any tendency for the jack to tilt or tip. At the same time, no hindrance is presented to the raising and lifting movements of the supporting member relative to the base occasioned by the operation of the actuating mechanism of the jack which assumes the form of a conventional screw spinelle which serves to vary the relative displacement between two spacer blocks, the displacement between which controls the positioning of the levers of the jack and the resultant distance between the supporting member and the base.

It is a further object of the invention to provide a base and supporting member of comparatively light material which nevertheless is strong and which assures a secure engagement of the base or supporting member with the surfaces adjacent thereto.

Other objects and purposes will appear from the detailed description of the invention following hereinafter, taken in conjunction with the accompanying drawings, wherein Fig. 1 is a plan view of the jack in accordance with the present invention;

Fig. 2 is a front elevation thereof showing an alternative raised'position of the jack in dotted lines;

Fig. 3 is a vertical sectional view along line 3 3 of Fig. 1;

Fig. 4 is a ver-tical sectional view alongline 4 4 of Fig, 2;

Fig. 5 is a vertical sectional view along line 5 5 of Fig. 1; and

Fig. 6 is a vertical sectional view' along line 6 6 of Fig. 1.

The jack shown inthe drawing is a screw opgratedv jack sometimes Vdesignated asa scissors type jack, embodying' a' base I0 and a supporting member 20 with a system of levers extending therebetween, explained. fully below, for the purpose of varying the relative spacing between the base and the supporting plate to ellect a raising or lowering of objects such as parts of automo- `biles, heavy loads, axles, etc. The positioning of the levers is modified by the rotation of a' screw spindle extendinghorizontally midway between the base and the surmortin'g plate and on which are mounted two variably spacedA bearing blocks interconnected with theV lever system, the adustable spacing of whichV controls the disposition of the levers.

The lever system of the disclosed embodiment is duplicated upon the opposite sides of the base and the supporting plate, `and to simplify their designation, corresponding reference numerals have been applied to bothA sets of levers, with one set being primed.

Figs. 1 and 2 show the base I 0 with crossed levers I and 2 pivotally mounted thereto at I3 and I2, respectively, at longitudinally displaced points on the base. The base I()V may be of channel configuration and the levers pivcted thereto may lie adjacent the vertical anges IIJ thereof. As shown in the drawings, common bolts', pins or rivets I2 and I3 extend across the complete width of the base I0 Yand pivotally `connect also the levers I and 2 on the opposite side of the base to the opposite flange I0 thereof.

Lever I extends upwardly from the base and is pivoted to a trunnion I8 extending from one of the spacer blocks I'I carrying the screwshaft or spindle 35. The lever 2 extends upwardly from the pivot I 2 and is pivoted to a trunnion I6 extending from the spacer block I5 supporting the rotary screw shaft 35. Also mounted onV the latter trunnion is one end of a lever 6 which extends upwardly from the block I5 and the opposite end of which is pivoted at 22 to the supporting member 20 at the flange 20 thereof. Similarly, another lever 5 extends upwardly from the trunnion I8 of block I1 and is pivoted to the supporting plate 20 at 23. Congruous levers 6 and 5 also extend upwardly from trunnions IB and I8', respectively, to member 20. The supporting plate 20 is similar in construction to the base I0, that is, it may be of channel configuration and the pivotal connections thereto are in the form of upset bolts or rivets extending through the vertical channels 20' to mount the congruent levers on the opposite sides of the supporting plate by the same rivets. Of course, it is understood .that bolts and nuts may be used in lieu of pins or rivets, or that separate pivotal mountings may be provided for each set of levers on the opposite sides of the base adjacent to the respective vertical flanges I and 2U.

An enlarged view of the blocks I and I1 and their relation to the rotary screw spindle 35 is visible in Fig. 3 Which shows an unthreaded portion of the screw shaft 36 rotatably mounted in the block I5. A socket element 31 is keyed to the end of the shaft 35 by a pin 38 and a thrust bearing 39 is disposed between the socket 31 in a recessed portion 43 of the block I5 (Fig. 6). The disc 39a of the thrust bearing 39 remains xed adjacent to the block I5 while the part 39h rotates easily with the spindle as a result of series of ball bearings 39e interposed between the races between the parts 39a and 391D.

A lever having al small crank offset is adapted to be rockably inserted through the enlarged open end 4I of socket 31, the crank of which eX- tends upwardly into the smaller opening 42 to provide an eiective coupling for the rotation of the screw shaft. Any other form of coupling unit may be provided at the end of the shaft for cooperation with a mechanical handle of a collapsible type for conveniently rotating the screw shaft.

As shown in Fig. 2, the effect of rotating the screw spindle serves to vary the spacing between the block I1 relative to thelxed block I5 on the spindle, which results in a modification of the arrangement of the levers I, 2, 5 and 6 on one side of the jack and the congruent levers I', 2', 5 and 6' on the other side of the jack to effect a raising or lowering of the load supported by the member 20 relative to the base I0. Jacks of this type are old in the art and these may employ two threaded blocks cooperating with a rotary screw spindle embodying oppositely threaded portions thereon to vary the spacing of the blocks thereon and to correspondingly vary the level of the lifting plate. The present invention presents improvements over jacks of this type by the incorporation of additional features which render the jack more rugged and reliable and stable under conditions of heavy and shifting loads.

To attain these new objectives, provision is made of additional or supplemental supporting levers 3 and 4 which are pivoted, respectively, to the points I2 and I3 and extend beyond the ends of the base I0. Corresponding levers 1 and 8 are pivotally connected to the supporting member 20 at 22 and 23, respectively. Levers 3 and 1, of the same length as levers I and 5, respectively, are pivotally joined at 26 to form two sets of parallelograms between the base I0 and supporting member 2li. Likewise, levers 4 and 8, of the same lengths as levers 2 and 6, are pivotally joined together at 25, to form two similar parallelograms in the opposite direction. A similar system of congruent levers 3-1' and 4'-8 are connected to the opposite sides of the base I0 and supporting member 20 as shown in Fig. 1 and are pivotally joined at 26' and 25. The sets of levers 8 4, 1-3, 8*-4 and 1-3 transmit the loads from the supporting member 20 to the base I0 without straining the loading on the blocks I5 or I1 or the screw shaft or spindle on which they are mounted to eliminate any tendency for the elements to buckle and become misaligned under heavy loading conditions.

An equalization of the loadings on the several levers forming parts of corresponding parallelograms may be attained by connecting a lever 30 between the pivot points 25 of the outside levers 4 and 8 and the trunnion I6 of the block I5 to which are connected the inside levers 2 and 6. The spacing on lever 30 between points 25 and I6 is the same as the spacing between pivots I2 and I3 on the base and 22 and 23 on the supporting member. This lever 30 may be extended across the complete length of the jack and is provided with a slight offset portion 3I. A channel member 40 may likewise be connected between the pivot 26 and trunnion I8 of the block I1, to provide for an equalization of the loading between the opposite sets of levers 1-3 and 5--I forming the corresponding opposite parallelograms. The spacing between 26 and I8 is the same as that between 25 and I6. The channel 40 is shown riveted at the pivot 26 and trunnion I8 and is provided with anges 48 extending in parallel to the base of the flange to form a guide track for the lever 30 as the same moves in parallel to the screw shaft and at the same level thereof. This accommodation of the lever 30 within the channel 4D is made possible by the oset portion 3l of the lever which is displaced by an amount corresponding to the thickness of the web of the channel as shown in Fig. 5. This coupling between the opposite ends of the jack, while affording the necessary freedom of movement therebetween, results in an equalization of loadings between the ends of the jack which would normally tend to tip the same.

In the illustrated embodiment of the invention, congruously disposed stabilizing bar 30' is mounted upon the opposite side of the jack between pivot 25 and trunnion I6 and channel 4U is riveted between pivotal joint 26 and trunnion I8 for cooperation with the extension of bar 3U. If desired, the disposition of the parts may be reversed on the opposite side, i. e., the channel 40 may be connected between points 25 and I6 and the bar 30' may be connected between points 26 and I8'. Furthermore, the advantages of the invention may be realized in different degrees by providing equalization of loadings between the different sets of levers at less than the four points shown in the preferred embodiment.

Transverse ribs II are formed on the bottom surface of the base I0 and corresponding ribs 2I are formed in the top surface of the supporting member 20 to improve the gripping surface of these members with the ground, the load or any other surface with which they may come in contact.

While we havev described our invention as embodied in a specic form and as operating in a specific manner for purposes of illustration, it should be understood that we do not limit our invention thereto, since various modifications will suggest themselves to those skilled in the art without departing from the spirit of our invention, the scope of which is set forth in the annexed claims.

We claim:

1. In a lifting device, two oppositely disposed bearing blocks, a base positioned below said blocks, a supporting member positioned above said blocks, a pair of crossing levers pivotally connected to each side of said base and said blocks, a pair of crossing levers pivotally connected to each side of said supporting member and said blocks, a rotatable screw spindle mounted in said blocks which when rotated in one direction draws said blocks together to raise said supporting member and when rotated in the opposite direction forces said blocks apart to lower said supporting member, a plurality of additional levers extending from each side of said base and said supporting member with the free ends of the respective pairs thereof pivotally connected to each other at the level of said blocks and the rotatable spindle extending therebetween, and bracing means extending at said level between at least some of said last-mentioned pivotal connections and the respective bearing block adjacent thereto comprising a horizontally disposed stabilizer bar extending from the connection thereof to the pivotal joint of a pair of said additional levers and the end of the bearing block adjacent thereto towards the opposite end of said lifting device.

2. In a lifting device, two oppositely disposed bearing blocks, a base positioned below said blocks, a supporting member positioned above said blocks, a pair of crossing levers pivotally connected to each side of said base and said blocks, a pair of crossing levers pivotally connected to each side of said supporting member and said blocks, a rotatable screw spindle mounted in said blocks which when rotated inf'one direction draws said blocks together to raise said supporting member and when rotated in the opposite direction forces said blocks apart to lower said supporting member, a plurality of additional levers extending from each side of said base and said supporting member with the free ends of the respective pairs thereof pivotally connected to each other at the level of said blocks and the rotatable spindle extending therebetween, and bracing means extending at said level between at least some of said last-mentioned pivotal connections and the respective bearing block adjacent thereto said bracing means extending parallel to said screw spindle at the level thereof and constrained to maintain said parallelism at all levels of said screw spindle between said base and said supporting member.

3. In a lifting device, two oppositely disposed bearing blocks, a base positioned below said blocks, a supporting member positioned above said blocks, a pair of crossing levers pivotally connected to each side of said base and said blocks, a pair of crossing levers pivotally connected to each side of said supporting member and said blocks, a rotatable screw spindle mounted in said blocks which when rotated in one direction draws said blocks together to raise said supporting member and when rotated in the opposite direction forces said blocks apart to lower said supporting member, a plurality of additional levers extending from each side of said base and said supporting member with the free ends of the respective pairs thereof pivotally connected to each other at the level of said blocks and the rotatable spindle extending therebetween, and bracing means extending at said level between at least some of said last-mentioned pivotal connections and the respective bearing block adjacent thereto comprising a horizontally disposed stabilizer bar extending from the connection thereof to the pivotal joint of a pair of said additional levers and the end of the bearing block adjacent thereto towards the opposite end of said lifting device, and a horizontally disposed guide channel at said last-mentioned end of said lifting device connected between another pair of said additional levers and the corresponding end of the bearing block adjacent thereto for guiding the free end of said stabilizer bar in the course of its movement relative to said guide channel as said bearing blocks move to-and-fro.

4. In a lifting device, two oppositely disposed bearing blocks, a base positioned below said blocks, a supporting member positioned above said blocks, a pair of crossing levers pivotally connected to each side 0f said base and said blocks, a pair of crossing levers pivotally connected to each side of said supporting member and said blocks, a rotatable screw spindle mounted in said blocks which when rotated in one direction draws said blocks together to raise said supporting member and when rotated in the opposite direction forces said blocks apart to lower said supporting member, a plurality of additional levers extending from each side of said base and said supporting member with the free ends of the respective pairs thereof pivotally connected to each other at the level of said blocks and the rotatable spindle extending therebetween, and bracing means extending at said level between at least some of said last-mentioned pivotal connections and the respective bearing block adjacent thereto, said bracing means at one end of the lifting device being in the form of horizontally disposed levers extending towards the opposite end of the lifting device and the bracing means at said last-mentioned end being in the form of horizontally disposed guide channels for guiding the free ends of said last-mentioned levers.

5. A jack comprising a base, pairs of crossing congruent levers pivotally mounted to said base at longitudinally displaced points thereon on the opposite sides of the longitudinal median of said base, a pair of bored spacer blocks pivotally mounted between the corresponding pairs of said congruent levers, at least one of which is internally threaded, a screw spindle rotatably mounted in said blocks for varying the spacing between said blocks by the rotation of said screw spindle, additional pairs of crossing congruent levers pivotally mounted on opposite ends of said blocks and extending upwardly therefrom, a supporting member pivotally mounted to the free ends of said last-mentioned levers, supplemental supporting levers pivotally mounted at one of the ends thereof to said base and to said supporting member around axes common to pivotal axes of said congruent crossing levers therewith and extending outwardly beyond said axes, pivotal connections between the opposite ends of corresponding pairs of said supplemental supporting levers at the level of said spacer blocks to form parallelograms with said crossing levers, a horizontal bracing bar extending between one of said last-mentioned pivotal connections and one end of the spacer block adjacent thereto towards the opposite end of said jack, and a guide channel connected between another one of said lastmentioned pivotal connections and the corresponding end of the spacer block at said last-mentioned end of said jack to serve as a guide for said bracing 7 bar to equalize the loadings on the jack therebetween.

6. A jack comprising a base, pairs of crossing congruent levers pivotally mounted to said base at longitudinally displaced points thereon on the opposite sides of the longitudinal median of said base, a pair of bored spacer blocks pivotally mounted between the corresponding pairs of said congruent levers, atleast one of which is internally threaded, a screw spindle rotatably mounted in said blocks for varying the spacing between said blocks by the rotation of said screw spindle, additional pairs of crossing congruent levers pivotally mounted on opposite ends of said blocks and extending upwardly therefrom, a supporting member pivotally mounted to the free ends of said last-mentioned levers, supplemental supporting levers pivotally mounted at one of the ends thereof to said base and to said supporting member around axes common to pivotal axes of said congruent crossing levers therewith and extending outwardly beyond said axes, pivotal connections between the opposite ends of corresponding pairs of said supplemental supporting levers at the level of said spacer blocks to form parallelograms with said crossing levers, a horizontal bracing bar extending between each one of a congruous pair of said last-mentioned pivotal connections and the corresponding end of the spacer block adjacent thereto towards the opposite end of said jack, and a guide channel connected between each one of another congruous pair of said last-mentioned pivotal connections and the corresponding end of the spacer block at said last-mentioned end of the jack, said guide channels adapted to serve as guides for the respective bracing bars to equalize the loadings on the jack between the sides and the ends thereof.

7. In a lifting device as set forth in claim 1, wherein said base and said supporting member are formed of sheet metal provided with projections on the surface thereof to secure a firm engagement with bodies in contact therewith.

8. A jack as set forth in claim 5 wherein said base and said supporting member are formed of sheet metal of channel formation provided with a plurality of projections in the web thereof extending transversely to the longitudinal axis of the jack, and said crossing and supplemental supporting levers are pivoted to the anges thereof.

PETER PLUTA. LESTER FELDERSTEIN.

REFERENCES CITED The following references are of record in the file of this patent: 

